Yeah, as I said in another comment, my dog did not do well when taking Benadryl -- he became more anxious. At the time we were not using it for the purpose of calming him, but instead to hopefully counteract some itching he seemed to be having in his ears. After about a week of increasing anxiety, we put 2 and 2 together, and realizing why he was acting SO insanely anxious... and I made a mental note that we won't be using that as an easy calming aid in the car.

So, I do hope with more time and trials, he will think of car rides as no biggie. We'll see!